Method for producing coordinate screens for cathode-ray oscilloscopes



NOV. 15, 1949 w LUBiN METHOD FOR PRODUCING COORDINATE SCREENS FOR CATHODE-RAY OSCILLOSCOPES Flled June 7 1945 INVENTOR. VW/fiam Lab/n ATTOE/VEX Patented Nov. 15, 1949 'i i: 1,

' METHOD For: PRODUCING. COORDINATE.

' SCREEN FQR;GATHODE-RAY OSCILLQ- SCOPES WilliamLubin, United States Navy Application June 7, 1945, SeriaLNo. 598,183

(Granted under they act of March 3, 1883, as

2 Claims.

This invention relates. ingeneral to a method;

for forming an auxiliary conforming screen; for cathode-ray tube.

An oscilloscope tube is essentially of the same exterior construction as the conventional cathode ray tube. These tubes comprise a highly evacuated envelope, usually of glass, having at one end integrally associated with the envelope a special translucent screen which fluoresces when a beam of electrons is directed thereonto. The end comprising the translucent screen is conventionally of convex shape to impart strength to the tube.

In an oscilloscope the electron beam is so deflected under varying conditions that a pattern is formed upon the fluorescent screen of the tube. It is frequently desirable to determine exactly the dimensions of the pattern upon the fluorescent screen. For this purpose transparent auxiliary screens having co-ordinate lines inscribed thereon have been placed in front of the oscilloscope screen. The auxiliary screen is often merely a flat window in an oscilloscope instrument panel having a coordinate system inscribed thereon.

and behind which the oscilloscope tube is installed. In using such an auxiliary screen p'arallax error is introduced due to the fact that the screen or Window upon which the coordinate lines are inscribed and the coordinate lines themselves are not of the same contour as the fluorescent screen upon which the image occurs.

An object of this invention is to provide a method of producing an oscilloscope screen having a concave surface with coordinate lines thereon.

Further objects and advantages of this invention, as well as its construction, arrangement and operation, will be apparent from the following description and claims in connection with the accompanying drawing in which Fig. 1 is a fragmentary side elevation representing the end of a conventional cathode-ray oscilloscope tube,

Fig. 2 is a sectional side elevation of a coordinate screen embodying this invention, and

Fig. 3 is a fragmentary front elevation of an oscilloscope instrument panel showing the coordinate screen of this invention installed therein.

Fig. 1 shows the end of a conventional cathode ray oscilloscope tube, generally designated as l I, having a fluorescent screen l2 of a convex shape.

Fig. 2 shows an auxiliary screen embodying this invention, consisting of a. plate of transparent material, such as clear, transparent, methacrylate resin called Lucite, generally desig- 56 amended April 30, 1928; 370 0. G. 757) nated. as lafone surface M of which: is-.;of suchconcavity asv substantially to fit, the convex end.

of the fluorescent screen l2. Upon the concave surface I4 is a system of coordinate lines I5. These lines are scribed or otherwise cut or impressed into the surface of the material and are filled with coloring matter such as India ink or other suitable opaque substance. It is essential that the coordinate system be curved to the same contour as the concave surface l4; straight lines projected onto the curved surface would introduce the same parallax error as would be introduced in using a flat plate. The coordinate lines 15 are therefore placed upon the curved surface ll of the screen l3 in such a manner that both vertical and horizontal lines correspond in contour substantially to arcs of the concave surface.

The concave screen I 3 may be placed in a panel board of an oscilloscope instrument as in Fig. 3, wherein l6 indicates the panel board, and I1 and I8 represent retaining ring and gasket respectively. The cathode ray oscilloscope II is installed behind the panel board l6 so that its end [2 fits snugly in the concave portion [4 of the screen l3.

This invention resides in the method of producing the coordinate screen described above. According to this method a system of coordinate lines is scribed or otherwise cut or impressed upon a flat surface of a plate of Lucite or other transparent material capable of being molded. These lines are filled with suitable coloring matter so as to make them stand out clearly and sharply. The plate is then molded in such a manner as to make the former flat surface containing the coordinate system conform in contour to the end of the tube of the cathode-ray oscilloscope so that the plate may be placed upon the end of the tube with the lined surface contacting the tube at substantially all points. In this manner the coordinate lines are curved in exactly the same manner as the fluorescent screen and the image upon the screen may be measured by reference to these the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. The method of producing a coordinate screen for cathode-ray oscilloscopes comprising inscribing one surface of a plate of transparent moldable material with a system of coordinate lines, and molding said surface of said inscribed plate to conform to the end contour of the tube of the cathode-ray oscilloscope whereby the lines of said system are curved in accordance with end contour of the tube and whereby, in turn, readings taken on said system of lines avoid parallax.

2. The method of producing a parallax-less coordinate screen for the arcuate end of a tube of a cathode-ray oscilloscope, said method comprising inscribing a system of coordinate lines upon a flat surface of transparent moldable material and thereafter molding said surface to conform to such arcuate end whereby a curvature is given to said lines and whereby, in turn, readings, taken on 4 said lines having said curvature, are without parallax.

WILLIAM LUBIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,063,870 Finch Dec. 8, 1936 2,091,152 Malpica Aug. 24, 1937 2,208,494 Broderson July 16, 1940 2,293,529 .Bedford Aug. 18, 1942 2,312,206 Calbick Feb. 23, 1943 2,316,777 Fell Apr. 20, 1943 2,330,604 Messner Sept. 28, 1943 2,346,810 Young Apr. 18, 1944 FOREIGN PATENTS Number Country Date 107,450 Austria May 16, 1939 

